Exhaust post-treatment devices frequently offer additional installations, which must be accommodated in diesel-engine drive systems by way of retrofitting or modification. However, even in new constructions, the additional consideration of a new exhaust post-treatment device frequently leads to considerable difficulties, because in addition to the space required for such devices, generally, it is undesirable to compromise the familiar appearance of the vehicle by incorporating such a device, or to do so only to an irrelevant extent.
In spite of the limitations resulting here, the exhaust post-treatment devices should show a design with regards to their structure, as well as with regards to cost aspects, which allow the necessary modification, at least without interfering with the respective design principle.
An exhaust post-treatment device in which the respective aspects have partially been considered is known from EP 1 644 621 B1. In this exhaust post-treatment device, an exhaust treatment arrangement is provided in a cylindrical housing, which comprises a soot filter unit and a denitrification-catalytic converter unit arranged lying concentrically in reference to each other, which are arranged between upstream and downstream supply connections, on the one side, and an axially opposite transition chamber, on the other side. Exhaust flows in via the upstream supply connection through the annular soot filter unit, encased by the housing, axially to the transition chamber, where it radially mouths out via helical guide channels, flown through in the same direction and off-set with regards to its influx and outlet cross-section by 180°, in outlet cross-sections facing each other allocated thereto. Starting at the transition or mixing chamber, axially the denitrification-catalytic converter unit is approached. Starting at the denitrification-catalytic converter unit, which is surrounded by the annular soot filter unit and which is axially flown through opposite in reference to the soot filter unit, the exhaust transfers to the downstream supply connection. When the denitrification-catalytic converter unit is embodied as a so-called SCR-catalytic converter, according to the explanations of WO 2004/113690 corresponding to the above-mentioned EP 1 644 621 B1, the injection of the urea solution occurs for denitrification purposes in the area of the mixing chamber.
In order to allow adjusting such an exhaust post-treatment device in its design to the requirements modified with regards to capacity, the device is variable with regards to the length of the soot filters and denitrification-catalytic converter units such that the transfer chamber is arranged in a removable end part of the housing and that based on the respective separation level via support devices of different lengths, differently long soot filter and denitrification-catalytic converter units of different lengths can be clamped in the device. This way, by the respective selection in the longitudinal measurement of its units it can be designed adjusted in its construction to the needs to a certain extent.
In another exhaust post-treatment device—DE 102 50 050 A1—with a cylindrical housing and axially opposite inlet and outlet connections the housing is axially chambered and the interior chamber of the housing is divided by intermediate panels into different functional areas. They result such that a soot filter unit is arranged annularly surrounding a central tube, axially passing through intermediate panels, and a nitrogen-catalytic converter unit is arranged axially off-set in reference thereto in an adjacent chamber. Starting on a facial inlet chamber with axially penetrating openings to an adjacent chamber, accepting the soot filter unit, the exhaust flows radially through the filter and radially enters the central tube. Here, at the input side the injection of urea occurs as reduction means, which mixes with the exhaust. At the outlet end the central tube mouths in a mixing chamber, from which the exhaust flows through the nitrogen-catalytic converter unit opposite in reference to the flow through the central tube and exits to a discharge chamber located between the chamber accepting the soot filter unit and the mixing chamber and is branched off the outlet connection.
In another exhaust post-treatment device known from DE 10 2004 043 931 A1 with an essentially cuboid cross-section, the soot filter unit and the reduction means-catalytic converter unit are located layered on top of each other in an opposite direction of flow through the soot filter unit and the reduction means-catalytic converter unit laterally in reference to the direction of flow and taper opposite to the face of the housing allocated to the supply connections to a transmission and mixing chamber, where the dosing of the reduction means also occurs. The soot filter unit is formed by a soot filter showing an approximately rectangular cross-section while the catalytic converter unit is composed of several circular cylindrical catalytic converter modules, which are arranged adjacent to the wall of the soot filter in two levels side-by-side overlapping each other, so that within the cuboid cross-sections of the soot filter a cube wall extends longitudinally and the catalytic converter modules assume the space between the soot filter and the opposite cuboid wall.